Upregulation of proteoglycans in the perilesion perimeter in ventral horns after spinal cord injury.

Spinal cord injury (SCI) results in pronounced focal tissue damage with subsequent formation of a glial scar that blocks axon regeneration and regrowth. Cellular changes and the composition of the extracellular matrix in regions distal from the injured area remain poorly characterized. In the present study, in the spinal cord distal to the damaged area (perilesion perimeter) there were minimal gross histological changes, but there were pronounced alterations in the extracellular proteoglycans even at 30 days after SCI. These abnormalities coincided with the appearance of reactive astrocytes and a reduction in main astrocytic glutamate transporter 1. Proteoglycan levels exhibited different kinetics and changes after SCI in areas near neuronal cell bodies and in areas distal from them. The results of the study suggest that SCI induces widespread changes in the spinal cord that may be responsible for neuronal dysfunction far from the damaged area and further aggravation of the SCI.

PTEN expression in astrocytic processes after spinal cord injury.

The role of the Rho/ROCK/PTEN signaling pathway in the regulation of astrocyte function for consolidation/stabilization of the synapse has not been thoroughly studied. In this study, the expression of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) in GFAP-positive astrocytic processes in the ventral horns (VH) of the rat spinal cord has been evaluated in the normal condition and in a delayed period (30 days) after dosed contusion spinal cord injury (SCI) in caudal thoracic segments. In intact rats and at 30 days post-injury (dpi), semi-quantitative immunohistochemical analysis showed that there is approximately 2 folds less synaptophysin reactivity in the motoneuron perikarya than outside the perikarya, i.e., on dendritic spines, in the VH area. At 30 dpi, the square occupied by synaptophysin reactivity on the motoneuron perikarya and dendritic spines decreased ~2.4 and ~2.1 folds, respectively. Western blotting of the postsynaptic density protein 95 (PSD95) showed a decreased amount in the area of injury of ~3 folds at 30 dpi. Expression of GFAP in the astrocytic processes around the synaptophysin spots (APAS) was less than in the astrocytic processes that were located at distance from the synapses (APFS) both in the intact and SCI groups. In the APAS, the expression level of PTEN increased significantly after SCI. In these astrocytic processes, the PTEN expression level was significantly higher than in the APFS for both the intact and SCI rats. In the intact spinal cord, different PTEN expression levels were detected both in APAS and APFS. This may be due to the varying degree of integration of PTEN in the membrane compartment of astrocyte stem processes and possibly the increased delivery of PTEN from the GFAP-positive stem into fine GFAP-negative peripheral processes. The observed shifts after SCI reflect the imbalance in the mechanisms of synaptic plasticity after injury. Thus, strategies that have been developed for the deletion or knockdown of the PTEN gene are quite promising.

Electrophysiological, Morphological, and Ultrastructural Features of the Injured Spinal Cord Tissue after Transplantation of Human Umbilical Cord Blood Mononuclear Cells Genetically Modified with the VEGF and GDNF Genes.

In this study, we examined the efficacy of human umbilical cord blood mononuclear cells (hUCB-MCs), genetically modified with the VEGF and GDNF genes using adenoviral vectors, on posttraumatic regeneration after transplantation into the site of spinal cord injury (SCI) in rats. Thirty days after SCI, followed by transplantation of nontransduced hUCB-MCs, we observed an improvement in H (latency period, LP) and M(Amax) waves, compared to the group without therapy after SCI. For genetically modified hUCB-MCs, there was improvement in Amax of M wave and LP of both the M and H waves. The ratio between Amax of the H and M waves (Hmax/Mmax) demonstrated that transplantation into the area of SCI of genetically modified hUCB-MCs was more effective than nontransduced hUCB-MCs. Spared tissue and myelinated fibers were increased at day 30 after SCI and transplantation of hUCB-MCs in the lateral and ventral funiculi 2.5 mm from the lesion epicenter. Transplantation of hUCB-MCs genetically modified with the VEGF and GNDF genes significantly increased the number of spared myelinated fibers (22-fold, P > 0.01) in the main corticospinal tract compared to the nontransduced ones. HNA+ cells with the morphology of phagocytes and microglia-like cells were found as compact clusters or cell bridges within the traumatic cavities that were lined by GFAP+ host astrocytes. Our results show that hUCB-MCs transplanted into the site of SCI improved regeneration and that hUCB-MCs genetically modified with the VEGF and GNDF genes were more effective than nontransduced hUCB-MCs.

Adenoviral vector carrying glial cell-derived neurotrophic factor for direct gene therapy in comparison with human umbilical cord blood cell-mediated therapy of spinal cord injury in rat.

STUDY DESIGN: Experimental study. OBJECTIVE: To evaluate the treatment of spinal cord injury with glial cell-derived neurotrophic factor (GDNF) delivered using an adenoviral vector (AdV-GDNF group) in comparison with treatment performed using human umbilical cord blood mononuclear cells (UCB-MCs)-transduced with an adenoviral vector carrying the GDNF gene (UCB-MCs+AdV-GDNF group) in rat. SETTING: Kazan, Russian Federation. METHODS: We examined the efficacy of AdV-GDNF and UCB-MCs+AdV-GDNF therapy by conducting behavioral tests on the animals and morphometric studies on the spinal cord, performing immunofluorescence analyses on glial cells, investigating the survival and migration potential of UCB-MCs, and evaluating the expression of the recombinant GDNF gene. RESULTS: At the 30th postoperative day, equal positive locomotor recovery was observed after both direct and cell-based GDNF therapy. However, after UCB-MCs-mediated GDNF therapy, the area of preserved tissue and the number of spared myelinated fibers were higher than those measured after direct GDNF gene therapy. Moreover, we observed distinct changes in the populations of glial cells; expression patterns of the specific markers for astrocytes (GFAP, S100B and AQP4), oligodendrocytes (PDGFαR and Cx47) and Schwann cells (P0) differed in various areas of the spinal cord of rats treated with AdV-GDNF and UCB-MCs+AdV-GDNF. CONCLUSION: The differences detected in the AdV-GDNF and UCB-MCs+AdV-GDNF groups could be partially explained by the action of UCB-MCs. We discuss the insufficiency and the advantages of these two methods of GDNF gene delivery into the spinal cord after traumatic injury.

Characterization of spinal cord glial cells in a model of hindlimb unloading in mice.

Exposure to microgravity has been shown to result in damaging alterations to skeletal muscle, bones, and inner organs. In this study, we investigated the effects of microgravity by using a hindlimb unloading model (HUM) in mice. The characteristics of the lumbar spinal cords of HUM mice 30 days after hindlimb unloading were examined. Morphometric analysis showed reductions of the total area, gray matter, and white matter by 17%, 20%, and 12%, respectively. Myelinated fibers in the white matter showed prominent myelin destruction. Analysis of the number of glial fibrillary acidic protein (GFAP+)/S100 calcium-binding protein B (S100B-), GFAP+/S100B+, and GFAP-/S100B+ astrocytes in the ventral horn (VH), central channel area (CC), dorsal root entry zone (DREZ), main corticospinal tract (CST), and ventral funiculi (VF) showed that the number of GFAP+/S100B- astrocytes was increased in the DREZ and CST of HUM mice. Additionally, GFAP+/S100B+ cell numbers were significantly decreased in the VH and CST but did not differ in the CC or DREZ of HUM mice, as compared with the control. The numbers of GFAP-/S100B+ cells were significantly reduced only in the VH of HUM mice. Moreover, the number of ionized calcium-binding adaptor molecule 1 (Iba1+) microglia cells was significantly increased in the CC and DREZ of HUM mice. In control mice, homeobox protein HoxB8 (HoxB8+) cells were found only in the CC; in contrast, HoxB8+ cells were observed in all studied areas in HUM mice, with the greatest number found in the CC. Genome-wide transcriptome analysis of the lumbar spinal cords of HUM mice showed decreased expression of genes encoding myelin, extracellular matrix, cytoskeleton, and cell adhesion proteins. Real-time polymerase chain reaction (PCR) confirmed reductions in the expression of mpz, pmp2, pmp22, and prx genes, which are involved in myelination, as well as decreases in the levels of genes encoding extracellular matrix molecules, including glycoproteins (matrix gla protein (MGP), osteoglycin (OGN), microfibrillar associated protein 5 (MFAP), and collagen, type IV, alpha 1 (COL4A)), proteoglycans (perlecan (heparan sulfate proteoglycan) (HSPG)), and metalloproteinases (lysyl oxidase (LOX)). Thus, our results showed that hindlimb unloading caused decreases in gray and white matter areas, changes in gene expression, alterations in myelination, and phenotypic modifications in glial cells in the lumbar spinal cords of mice.

Satellite cells of sensory neurons after various types of sciatic nerve trauma in the rat.

Sciatic nerve crushing, transection, and ligation models were used in rats to study the reactions of and changes in the numbers of satellite cells (SC) in spinal dorsal root ganglia in the lumbar segment. Nerve transection was followed by the appearance of neurons surrounded by two layers of SC. The thickness of SC processes and the areas of contacts with neurons increased as a result of invaginations into neuron perikarya. After nerve ligation, SC and their processes were located around parts of large and intermediate neurons in several tightly appressed layers; the area of contact between SC and neuron perikarya showed increased development of invaginations such that lamellar structures appeared in the SC cytoplasm, along with contacts with SC processes surrounding neighboring neurons. The greatest increases in SC numbers were seen after ligation of the nerve. Transection was followed by increases in the numbers of small and intermediate neurons surrounded by vimentin-positive SC. The number of large neurons surrounded by these cells decreased. At all time points following ligation of the nerve, all neurons in the study ganglia were surrounded by vimentin-positive SC. Post-traumatic changes in structure and numbers differed in SC associated with sensory neurons of individual size populations and depended on the type of trauma applied to efferent conductors.

Morphofunctional analysis of experimental model of esophageal achalasia in rats.

We carried out a detailed analysis of rat model of esophageal achalasia previously developed by us. Manifest morphological and functional disorders were observed in experimental achalasia: hyperplasia of the squamous epithelium, reduced number of nerve fibers, excessive growth of fibrous connective tissue in the esophageal wall, high contractile activity of the lower esophageal sphincter, and reduced motility of the longitudinal muscle layer. Changes in rat esophagus observed in experimental achalasia largely correlate with those in esophageal achalasia in humans. Hence, our experimental model can be used for the development of new methods of disease treatment.

Immunohistochemical study of rat soleus muscle in various modes of denervation.

Immunohistochemical study with monoclonal antibodies against fast myosin heavy chains showed that excision of a fragment of sciatic nerve does not change, while compression of the nerve decreased the relative content of fast muscle fibers in rat soleus muscle. The content of fast fibers in the muscles of contralateral limbs decreased in both models of denervation. Hence, contralateral limbs cannot be used as the control in experiments with disturbed neurotrophic function. Possible mechanisms underlying changes in the immunohistochemical profiles of experimental and contralateral limbs are discussed.

Effect of xymedon on cell survival in the system sensory neuron Schwann cell.

Pyrimidine derivative xymedon inhibits neuronal death in L4-L5 spinal ganglia 30 days after ligation of rat sciatic nerve. After treatment with xymedon the number of neurons on the operated side decreased by 22.1% compared to that on the contralateral side, while in the control group this parameter decreased by 28.7%. At the same terms, the number of Schwann cells on the operated side after xymedon injection increased by 27.7% in comparison with that on the contralateral side, while in the control group this parameter decreased by 57.3%.